Method of injection of fuel for internal combustion engines



F. RocHEFoR'r METHOD OF INJECTION OF FUEL FOR INTERNAL COllBl ISTIONENGINES Sept. 1

Filed 27. 1927 Patented Sept. 1 1 9 3 1 FRANQOIS ROCHEFORT, OF PARIS,FRANCE INIIEI'JPHOD F INJECTION OF FUEL FQR INTERNAL COMBUSTION ENGIN'ESApplication filed May 27, 1927, Serial No. 194,768, and in Trance June3, 1926.

The present invention relates to the direct supply of fuel to internalcombustion en gines in general, and more particularly to engines inwhich the opening of the atomizer 5 or injection valve is efiected bythe fuel itself, forced under pressure by the feed pump or distributer.

) Numerous arrangements are already known for injecting fuel byutilizing compressed air alone as the mechanical agent for atomizing anddiffusing the liquid fuel. Arrangements are also knownin which the fuelis broken up or atomized by compressed air or gas within the injectorand during the period of injection and diffusion in the interior of theengine cylinder.

In order to retain the advantages resulting from injection by ineans ofcompressed air or compressed gas, whilst avoiding the use of anauxiliary compressor, which the case of light, high-speed and low-powerengines, may constitute a complication and a source of trouble b reasonof the delicacy of working of this ind of apparatus, it has beenproposed to provide a small chamber for storing up hot air and gasesdrawn off from the working cylinder during the preceding compression andcombustion strokes or phases; these gases afterwards serve for iatomizing and diffusing the fuel at the molment of injection, byprojection of the fuel into the working cylinder at the moment of theopening of the injection valve.

But these arrangements involve numerous inconveniences 1. The air andthe gas are drawn or tapped off from the Working cylinder by means of apoppet valve or an automatic non-return valve, which cannot ensureaccuracy as regards its opening and closing.

. 2. The drawing off of the burning gases from the cylider involves alessening of the useful driving force, which is in general a greaterdrawbackto efficiency than would be the use of an auxiliary compressor,considering the enormous fall of temperature suffered by these gasesduring the time of their storage in the chamber.

3. These gases, being already burnt, have thus become inert and theirintroduction into the working cylinder during the injection prevents ahomogeneous mixture bemg obtained and affects the rapidity of combus- 4.It is impossible to avoid the carry-over of residues of combustion intothe chamber by these burnt gases; the result is that in the latter thereare formed carbon deposits which prevent the valves or injection needlesbeing kept tight, and in generahrapidly foul the pipes through which thefluid or the two I place in a form too massive to permit the employmentof high working speeds of the engines, and vaporized liquid fuel isfound in the exhaust gases; this fuel has therefore been evacuatedwithout having been able to burn inside the cylinder during theinsufficient time of the combustion period- -The present invention hasfor object to remedy these drawbacks and to improve considerably theresults obtained by compressed- ,air or compressed-gas injection, inorder to permit also the reasoned use of high tension electricalignition, exactly as for a mixture of air and petroleum spirit, butwhile utilizing heavy oils, mineral or vegetable, as fuel; thiselectrical ignition constitutes in effect an essential condition-forobtaining high speeds of rotation and wide limits of working, whichensure the flexibility in working'of the petroleum spirit engine.

. In conformity with the mvention, there is provided ":(fllllllllfll'communicating with the working cylinder by nozzles or twyers controlledby a valve, serving at the same time for the injection of the liquidfuel, and operated by the liquid fuel delivered under pressure in such away that the latter, already squeezed or reduced to a film and atomizedat the time of its admission by the,

injection valve, is not, towards the end of j the period of compressionin the cylinder, by a part of the carburcttcd mixture compressed in thecylinder and flowing through v I these nozzles or twyers, and is carriedalong into the chamber, passing through the injection valve, whichlatter isclosed from just before the point of ignition untilthe'commencement of the following compression stroke, when the mixture,vaporized in the chamber, returns by the twyers into the workingcylinder, by reason of the differenceof 1pressure between the chamberand the wor ing cylinder, before being compressed and ignited, whilst apart of the resh carburetted mixture is directed into the chamber at theend of period.

The principal agent for diffusing the fuel in the working cylinder isthus formed by a part of the carburetted mixture, drawn off thiscompression from the working cylinder at the end of the liquid fuel,distributed gradually during thecharging period, is reduced toa film andatomized mechanically by the valve, whilst the hot carburetted mixturecoming from the working cylinder ensures the diflusion of this fuel inthe mixture chamber or capacity. The delivery of fuel by the distributorceases *just before the mechanically operated closrangement according tothe invention in its ing of the injection valve. The fuel is sub- 1jected to a vaporization as complete as possible in the capacity servingas mixture;

chamber, which is maintained. in any suitable manner at a temperaturefavourable to this vaporization, but lower than the ignition temperatureof the gaseous mixture compressed in this chamber. On the other hand thecommunication between the chamber and the engine cylinder beingsuppressed by the positive closing of the injection valve just beforeignition in the cylinder, no burning gas can penetrate into thischamber; vaporization takes place rapidly during the whole time thatthis chamber remains closed.

The invention is applicable both to fourstroke engines and 'totwo-stroke engines; the annexed drawing represents by way of example, inaxial vertical section, the arapplic'ation to a two-stroke engine.

Above theworking cylinder a there is provided acha'mber b communicatingwith the interior of the cylinder by means of nozzles or twyers 0arranged in suitable number and in a circle around the axis of thefuel-injection v valve. This valve is composedof a'flat body d, which isdesigned to recall spring e bear upon a flat seating 12 formed in thewall of the chamber 6 and which is integral with a cylindrical portional in the shape of a piston, located in a cylindrical bore 6 formed inthe thickness of the wall of the chamber 6. The external diameter ofthis piston is slightly less than the internal diam- .sure by thedistributor (not shown), which is connected with a passage 12 formed inthe thickness of the wall of the chamber 2) and extending below thepiston d to the bottom of the cylindrical bore 12 serving as housing forthe latter. Under the pressure of this fuel, delivered at the correctmoment and for a suitable duration by the injection pump, the piston (Zis lifted, carrying with it the valve (1 which is slightly separatedfrom the seat 6 the liquid fuel passes through the very small butexactly calibrated annular clearance formed between the cylindricalpiston (l and its housing b and arrives in the form of a thin filmbetween the valve (l and its fiat seating 12 The height of lift of thevalve cl is limited by an. abutment rod 6, arranged and guidedvertically in the upper part of the chamber .12, in a plug f screwedinto the latter; this rod 6 carries-a ball e which comes-into engagementwith one of the extremities of a rocking lever g, pivoted at g andconnected at g to the operating mechanism (not shown) for closing thevalve (Z. The rod e is subjected to the action of a coiled spring awhich surrounds it and tends constantly to maintain the lower extremityof the rod (1 separated from the ribs at the upper part of the valve(Z;the fuel, delivered under pressure by the distributor, need nottherefore,

in order to lift the valve (1 from its seat If, ever lift the rod 6, buthas solely to overcome the inertia of the valve (Z (P, which is veryslight by reason of the fact that the piston d and the valve (Z arehollow. A cap 6 screwed upon the central part of the plug f, around theball abutment c limits the lift of the rod 6 under the action of its Inthe mechanism effecting the closing of the valve, there is interposed aspring or other elastic device (not shown), in such away as to preventdamage to the parts when the rod 6, under the action of'the rockinglever 9, brings the valve (I back upon its seat 6 thereby cutting offthe admission of liquid fuel.

For the explanation of the working of i this arrangement, it. will firstbe supposed "that the engine is running normally and that the chamber 5is. filled with a carburetted mixture which has been supplied thereintoat the end of a preceding compression stroke, as will be hereafterexplained.

At the beginning of the period of compression in the working cylindera,-'after the closing of the one, or more scavengingair admissionorifices a which takes place with a certain delay relative to theclosing of the one or more exhaust ports aF, that is to say when thepiston in its upward movement reaches the position 1:1 in the cylinder,insuch a Way as to ensure a full charge and even a supercharge in thecylinder,the fuel distributor commences to deliver the fuel, whichdetermines the opening of the injection valve (l; The admission of fuel,between the flat valve d and its seating 6 takes place at first with avery small output, which proceeds to increase gradually. At this moment,the rich carburetted mixture, which is in the chamber 1) at a pressurevery near the final pressure of compression, expands violently into theworking cylinder a, passing beneath the valve cl and through the nozzles0; these latter are formed and arranged in such a manner as to obtainthe maximum transferespeed of the fluid for a fixed relation of thepressures respectively existing in the working cylinder a. and in thechamber b during the injection stage. This injection into the workingcylinder takes place at the moment when the whole air is still in motionin the latter;

6; this equilibrium is afterwards'upset, the pressure becoming higher inthe working cylinder. The delivery-speed of *the fuelpump is thenaccelerated the valve (1, of which the lift is then limited by its stop6, is unable to rise further from its seating; the liquid fuel admittedby this valve is then squeezed or reduced to a film and atomizedmechanically by the calibrated clearance formed between the smallvalve-guiding piston (Z and its housing b i The speedof the workingpiston increasing (for example when the piston has arrived at theposition 2-2 in its upward stroke), by reason of the excess pressure inthe cylinder a, the carburetted air passes at high speed through thenozzles or twyers 0, in a direction opposite to the flow of thecarburetted mixture at the beginning of thecomp'ression stroke; thiscarburetted air carries along the greater part of the liquid fuel chargeadmitted by the valve J, diffusing this fuel in the chamber 6 whereinthe mixture is vaporized; for this purpose, the

chamber is protected against external radiation by a casing h and isheated by an electrical resistance 2' arranged within the chamber 6;this resistance takes the form of con centric rings separated? byinsulators and connected electrically on the one hand to the wall of thechamber 1), forming an earth return, and on the other hand to anelectrical conductor 2 connected to any suitable source of current. Thisresistance, at the time of starting and at moments when it is necessary,is raised by the passage of a current to a temperature which ensures themaintenance Within the chamber 6 of a temperature favourable to thevaporization of 'the carburetted mixture contained in the latter, butlower than the point of ignition of the rich mixture compressed therein.

This chamber 6 might also be heated by a supply of exterior wheat or,previously to using heavy oil, by running the engine on motor spirit forsome short time.

the cylinder a into the chamber b. The ignition of the charge ispreferably carried out by means of one or'more high tension sparkingplugs arranged atafi.

"Vaporization continues in the chamber 6.

during the whole of the time during which this chamber remains closed,that is to say during the period of combustion, expansion and exhaust,until the start of the following compression stroke, when the opening ofthe injection valve (Z allows the suitably vaporized carburetted mixtureto return fromthe chamber 1) into the cylinder.

The chamber 12 should preferably'be of a shape ensuring a completeevacuation of the still liquid fuel during the injection into theworking cylinder, at the beginning of the period of compression.

It is to be noted that the charge from the chamber 6 is in no wayderived or drawn off from the normal cylinder-charge, because thischamber b discharges itself into the working cylinder when the latterhas been completely filled, and when all the distribution orifices areclosed at the start of the compression stroke, and an equivalent chargepasses back from the cylinder into the mixing chamber at the end of theperiod of compression. There is thus a simple exchange of gaseous massesof different qualities without variation of quantity.

It may be remarked that the ignition is greatly facilitated by the factthat each time there is withdrawn from the cylinder a charge ofcarburetted air, which is injected anew into the working cylinder aftervaporization in the mixing chamber before being ignited.

At the time of starting the engine, since the chamber 6 does not enclosear'charge of carburetted air, there occur several up and down strokes ofthe piston in the cylinder before ignition takes place; the aircompressed by the piston carries along and diffuses in the chamberliquid fuel squeezed out and atomized mechanically bythe valve d; thecarburetted mixture is admitted into the cylinder at the beginning ofthe next compression stroke, merely to be forced back into the chamber 6with a new charge of air and fuel at the end of the period ofcompression; these operations are repeated until the mixture issuiiiciently carburetted and sufliciently vaporized to permit itsignition.

There maybe mixed, with'the charge of carburetted air in thevaporization chamber,

a gas which would be diffused at the same time as the mixture, in orderto activate the combustion of heavv fuel oils; this gas might also be acombustible gas.

In the case of, an engine ,with several cylinders, all the mixing andvaporizing chambers of the different cylinders may be connected togetherby pipes of very small sectional area, so as to equalize the pressuresand the speeds of, injection between all the cylinders. 7

It is to be understood that without in any way departing from the.principle of the" present invention, numerous modifications in detailmay be made in the form. of constr uction which has been illustrated anddescribed by way "of example. Thus, one

'might employ another type of valve for the injection of the fuel, forinstance those descrlberl in my prior patent speclfications Bro.197,934: and No. 923,468.

\Vhat I claim is: I 1. The method of operating an internalcombustionengine which comprises, providingtwo normally segregatedbodies of gaseous nature, one body being located within the compressionchamber of the engine, subject to compressive variations incident to thechange of capacity of said compression chamber, and the other body beingdefinitely bounded outside the compression chamber, placing said bodiesinto restricted communication during the compression stroke of theengine, thereby producing a tidal flow from the outside body to the onewithin the compression chamber on the early phase of the compressionstroke, and in; contra-direction on the later phase of the compressionstroke,

admitting liquid fuel under pressure in the form of a film to said.bodies at sald point of. restricted communication during the period oftheir tidal flow, and controlling the duration of said restrictedcommunicatlon, thoroughly pulverizing said liquid fuel of restrictedcommunication during period of their tidal flow, and controlling the bymeans of the tidal flow from the outside body to the one Within thecompression chamber on the early phase of the compression stroke, and incontradistinction on the later phase of the compression stroke trappingthe outside body of gaseous matter thus enriched with liquid fuel bypositively cutting off said restricted communication just prevlous tothe ignition point 1n said compression chamber and maintaining it cutoff until the beginning of the next compresv sion stroke, and thoroughlyvaporizing said trapped body of gaseous matter.

2. The method of "operating an internal combustion engine whichcomprises, providing "two normally segregated bodies of gaseous matter,one body being located within the compression chamber of the engine,subject to compressive variations incident to the change of capacity ofsaid compression chamber, and the other body being definitely boundedoutside the compression chamber, placing said bodies into restrictedcommunication during the compression stroke of the engine, therebyproducing a tidal flow from the outside body to the one within thecompression chamber on the early phase of the compression stroke, and incontra-direction on the later phase of the compression stroke,

admitting liquid fuel under pressure in the fornn of a film to saidbodies at said point the duration of said restricted communication,thoroughly pulverizing said liquid fuel by means of. the tidal flow fromthe outside body to the one within the compression chamber on the earlyphase of the compression stroke, and in contradistinction on the laterphase of the compression stroke trapping the outside body of gaseousmatter FRANQOIS ROGHEFORT.

